Method and system for releasing jamming of locking pin by use of holding control

ABSTRACT

A method for releasing jamming of a locking pin by use of holding control may include preparing the rotation of a camshaft so that the camshaft rotates in a target direction in a state in which the locking pin is jammed in a locking pin hole; applying a signal for releasing the locking pin from the locking pin hole; performing holding control so that a signal for rotating the camshaft is not applied for a predetermined reference time; and rotating the camshaft in the target direction after the locking pin is released by the performing of the holding control.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent Application Number 10-2014-0164882 filed on Nov. 25, 2014, the entire contents of which application are incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to a method and system for releasing jamming of a locking pin by use of holding control. More particularly, the present invention relates to a method and system for releasing jamming of a locking pin by use of holding control for securing a time for which the locking pin can be released during a predetermined reference time in order to solve a problem in that the locking pin becomes jammed by a ‘side force’.

2. Description of Related Art

For helping understanding of the present invention, a locking pin in a continuous variable valve timing (CVVT) will be described as follows.

In general, CVVT is a system that continuously changes the opening/closing time of a valve by changing the phase of a camshaft depending on an engine rotational frequency and a load state of a vehicle.

A conventional CVVT 101 of a vehicle, as shown in FIG. 1, generally includes a crank angle sensor for sensing a rotational angle of a crankshaft, a cam angle sensor for sensing a rotational angle of a camshaft 104, a variable valve timing unit 150 connected to one side of the camshaft 104 by a timing belt to allow the angle of the camshaft 104 to be advanced or retarded, and an engine control unit (ECU) for controlling an oil control valve 108 so that oil is supplied into an advanced angle chamber 111 a or retarded angle chamber 111 b of the variable valve timing unit 150 based on signals of the crank angle sensor and the cam angle sensor.

The variable valve timing unit 150 is configured with a stator 110 connected to the crankshaft by the timing belt to receive a turning force of the crankshaft, and a vane-shaped rotor 120 integrally coupled to the camshaft 104 to relatively rotate with respect to the stator 110.

A chamber 111 divided into the advanced angle chamber 111 a and the retarded angle chamber 111 b by the rotor 120 is formed in the stator 110. If oil is supplied into the advanced angle chamber 111 a through the oil control valve 108, the camshaft 104 rotates due to the generation of a phase difference between the rotator 120 and the stator 110, thereby changing the timing of the valve.

If the oil is flowed into the retarded chamber 111 b through the oil control valve 108, a phase difference occurs in the opposite direction between the rotor 120 and the stator 110, and therefore, the timing of the valve is delayed.

A locking pin 131 is formed in the rotor 120 so that the rotor 120 is locked to the stator 110 when an engine is stopped, and a pin holding part (not shown) for allowing the locking pin 131 to be held thereto is formed in the stator 110.

However, in the conventional CVVT 101 of the vehicle, a problem occurs in that the locking pin 131 is not appropriately held to the pin holding part when the engine is stopped, that the locking pin 131 does not move due to a physical limitation even though electronic control is performed, or that the locking pin 131 is stuck by a foreign substance.

Meanwhile, the ECU electronically controls a locking/unlocking operation with respect to a locking pin hole formed in the rotor 120 of the locking pin 131 by applying current to the oil control valve 108.

However, if a cam is driven before the locking pin 131 is completely separated from the locking pin hole, a problem may occur in that the locking pin 131 becomes physically jammed in a peripheral device thereof, that the locking pin 131 is stuck by a foreign substance, or the like. When the locking pin 131 is not separated from the locking pin hole as described above, the operation of the CVVT is not performed. In addition, the position of the cam does not smoothly follow a predetermined target value, and therefore, an engine warning light may be triggered. As a result, a driver should directly visit a vehicle service center.

A schematic view representing a problem in that the locking pin 131 becomes jammed in the locking pin hole formed in the rotor has been illustrated in FIG. 2.

As shown in FIG. 2, the locking pin 131 is released with respect to the locking pin hole by moving in the lower direction of the locking pin hole, and the control of the CVVT is then performed so that the cam should rotate in an advanced angle direction or a retarded angle direction. However, if the control of the CVVT is first performed as oil is supplied to the oil control valve 108 before the locking pin 131 is released, the side rotational force (side force) generated by a force with which the locking pin 131 rotates is greater than the unlock force that is a force advancing in the lower direction of the locking pin 131. Hence, the release of the locking pin is not performed.

Therefore, when the locking pin is not separated from the locking pin hole as described above, the operation of the CVVT is not performed. In addition, the position of the cam does not smoothly follow a predetermined target value, and therefore, an engine warning light may be triggered. As a result, a driver should directly visit a vehicle service center.

Accordingly, in order to solve a conventional problem in that the cam does not smoothly rotate in a target direction thereof due to jamming of the locking pin in the locking pin hole, the present invention provides a method and system for releasing jamming of a locking pin, which sufficiently secures a release time for which the locking pin is first separated from a locking pin hole by use of holding control for stopping the rotation of a cam in a target direction during a predetermined time.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a method and system for releasing jamming of a locking pin by use of holding control, which sufficiently secures a release time of the locking pin with respect to a locking pin hole so that a ‘side force’ generated by the rotation of a camshaft is not applied to the locking pin.

In accordance with an aspect of the present invention, there is provided a method for releasing jamming of a locking pin by use of holding control, the method including: preparing the rotation of a camshaft so that the camshaft rotates in a target direction in a state in which the locking pin is jammed in a locking pin hole; applying a signal for releasing the locking pin from the locking pin hole; performing holding control so that a signal for rotating the camshaft is not applied for a predetermined reference time; and rotating the camshaft in the target direction after the locking pin is released by the performing of the holding control.

In the preparing of the rotation of the camshaft, oil may be supplied into an advance angle chamber and a retard angle chamber by applying current to an oil control valve.

In the performing of the holding control, the predetermined reference time may exceed 0.2 seconds, and current for inducing rotation of the camshaft may not be applied to the oil control valve during the predetermined reference time.

In accordance with another aspect of the present invention, there is provided a system for releasing jamming of a locking pin by use of holding control, the system including: an oil control valve; and a controller for applying current to the oil control valve to induce the rotation of a camshaft in a target direction and the release of the locking pin, wherein the controller simultaneously applies, to the oil control valve, current for inducing the release of the locking pin and a signal for stopping the rotation of the camshaft during a predetermined reference time.

The controller may apply current to the oil control valve so that the camshaft rotates in the target direction after the release of the locking pin from a locking pin hole is induced by stopping the rotation of the camshaft during the predetermined reference time.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration view of a conventional continuous variable valve timing (CVVT).

FIG. 2 is a schematic view illustrating a problem in that a locking pin becomes jammed in a locking pin hole under control of the conventional CVVT.

FIG. 3 and FIG. 4 are flowcharts illustrating a method for releasing jamming of a locking pin by use of holding control in accordance with an exemplary embodiment of the present invention.

FIG. 5 is an entire configuration view illustrating a system for releasing jamming of a locking pin by use of holding control in accordance with an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

The present invention performs a control logic for releasing jamming of a locking pin, in which a control signal for releasing a locking pin 131 and a holding control signal for stopping the rotation of a camshaft 104 are simultaneously applied from a locking pin hole 120 a in order to prevent the rotation of the camshaft 104 from being performed when the locking pin 131 becomes jammed in the locking pin hole 120 a while the camshaft 104 rotates.

That is, as described above, in the conventional art, a problem occurs in that the camshaft 104 does not smoothly rotate in a target direction thereof as the locking pin becomes jammed in the locking pin hole 120 a by a ‘side force’ generated by the rotation of the camshaft 104 in an advanced angle direction or retarded angle direction before a release process in which the locking pin is separated from the locking pin hole 120 a. Thus, in order to solve this problem, the present invention applies a holding control signal for holding the rotation of the camshaft 104 during a predetermined reference time in order to secure a sufficient time for which the locking pin 131 can be released from the locking pin hole 120 a.

Accordingly, it is possible to prevent jamming of the locking pin, caused by a ‘side force’, during a sufficient time. Further, it is possible to control the camshaft 104 to rotate in the original target direction after the locking pin 131 is released from the locking pin hole 120 a.

The control logic for releasing the jamming of the locking pin will be described in detail with reference to FIGS. 3 and 4.

The control logic of the present invention includes preparing the rotation of the camshaft (S100), applying a signal for releasing the locking pin (S200), performing holding control (S300), and rotating the camshaft in a target direction (S400).

The preparing of the rotation of the camshaft (S100) is a preparation step before the camshaft 104 rotates in the target direction in a state in which the locking pin 131 is jammed in the locking pin hole 120 a. Specifically, in the preparation step, a bypass valve for connecting an advance angle chamber 111 a and a retard angle chamber 111 b is opened, and oil is supplied into the advance angle chamber 111 a and the retard angle chamber 111 b, so that the oil pressures in both the chambers are equalized. Thus, the camshaft 104 does not rotate in any direction.

That is, an engine control unit (ECU) 100 transmits, to an oil control valve 108, a current application signal for allowing oil to be supplied into the advance angle chamber 111 a and the retard angle chamber 111 b, and the oil control valve 108 receiving the transmitted current application signal supplies the oil through the valve connected to the advance angle chamber 111 a and the retard angle chamber 111 b, thereby providing the preparation step described above.

Subsequently, a step of applying a release signal for enabling the locking pin 131 to be separated from the locking pin hole 120 a is performed. In the step, the ECU 100 transmits a current application signal to the oil control valve 108 so that the locking pin 131 can be released, and the locking pin 131 is released from the locking pin hole 120 a by the oil control valve 108 receiving the transmitted signal.

That is, a step of releasing the locking pin 131 from the locking pin hole 120 a should be first performed so that the camshaft 104 rotates by an advance angle or retard angle in the target direction. Conventionally, a problem occurs in that the rotation of the camshaft was not smoothly performed by the ‘side force’ generated as the camshaft rotated before the locking pin was released.

Accordingly, the present invention secures a sufficient time for which the locking pin 131 can be separated from the locking pin hole 120 a by use of holding control for temporarily stopping the process in which the camshaft 104 rotates in the target direction, thereby solving the conventional problem.

That is, in the performing of the holding control, a signal for rotating the camshaft 104 is not applied during a predetermined reference time, so that it is possible to prevent a problem in that the locking pin becomes jammed by a ‘side force’.

In order to perform the holding control, the ECU 100 temporarily stops the current application signal for rotating the camshaft 104 from being supplied to the oil control valve 108 during the predetermined reference time. The predetermined reference time preferably exceeds 0.2 seconds.

During a time that exceeds 0.2 seconds, current for inducing the rotation of the camshaft 104 is not applied to the oil control valve 108, and simultaneously, a signal for releasing the locking pin 131 from the locking pin hole 120 a is applied to the oil control valve 108, so that it is possible to prevent the problem in which the locking pin 131 is jammed in the locking pin hole 120 a by the ‘side force’.

After the locking pin 131 is separated from the locking pin hole 120 a through the performing of the holding control, the ECU again applies current to the oil control valve 108, so that the camshaft 104 can rotate in the original target direction.

Meanwhile, FIG. 5 is an entire configuration view illustrating a system for releasing jamming of a locking pin by use of holding control in accordance with an exemplary embodiment of the present invention. As shown in this figure, the system includes an oil control valve (OCV) 108 and a controller 100.

The controller 100 is preferably an ‘ECU’. As oil is supplied into the advance angle chamber 111 a and the retard angle chamber 111 b by the oil control valve 108, the camshaft 104 rotates in the target direction.

The oil control valve 108 receives a current application signal for releasing the locking pin 131, transmitted from the ‘ECU’, to performing a process of releasing the locking pin.

The controller 100 simultaneously applies, to the oil control valve 108, current for inducing release of the locking pin 131 and a signal for stopping the rotation of the camshaft 104 during a predetermined reference time. After the release of the locking pin 131 from the locking pin hole 120 a is induced by stopping the rotation of the camshaft 104 during the predetermined reference time, current is applied to the oil control valve 108 so that the camshaft 104 rotates in the target direction.

In accordance with the method and system of the present invention configured as described above, it is possible to solve problems, such as the responsive character of the engine is lowered due to sticking of the locking pin, the driving performance is deteriorated, the engine is stopped, the starting performance is inferior, and the like. Further, it is possible to provide various advantages, such as the system of the CVVT can be effectively optimized, e.g., the sticking of the locking pin is solved without directly visiting a vehicle service center, and the like.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. A method for releasing jamming of a locking pin by use of holding control, the method comprising: preparing a rotation of a camshaft, wherein the camshaft rotates in a target direction in a state in which the locking pin is jammed in a locking pin hole; applying a signal for releasing the locking pin from the locking pin hole; performing the holding control so that a signal for rotating the camshaft is not applied for a predetermined reference time; and rotating the camshaft in the target direction after the locking pin is released by the performing of the holding control.
 2. The method of claim 1, wherein, in the preparing of the rotation of the camshaft, an oil is supplied into an advance angle chamber and a retard angle chamber by applying a current to an oil control valve.
 3. The method of claim 1, wherein, in the performing of the holding control, the predetermined reference time exceeds 0.2 seconds, and the current for inducing rotation of the camshaft is not applied to the oil control valve during the predetermined reference time.
 4. A system for releasing jamming of a locking pin by use of holding control, the system comprising: an oil control valve; and a controller for applying a current to the oil control valve to induce a rotation of a camshaft in a target direction and a release of the locking pin, wherein the controller simultaneously applies, to the oil control valve, current for inducing the release of the locking pin and a signal for stopping the rotation of the camshaft during a predetermined reference time.
 5. The system of claim 4, wherein the controller applies a current to the oil control valve so that the camshaft rotates in the target direction after the release of the locking pin from a locking pin hole is induced by stopping the rotation of the camshaft during the predetermined reference time. 